The RTHM series rotary stages provide arc-second resolution when driven from a micro-stepping or a brushless servo motor controller. The low profile design is made possible by the use of compact precision bearings. The rotating carriage of the stage provides continuous rotation of load up to 10 kg and has large clear aperture to allow the passage of the optical path or cables directly through the stage. The main body of the stages is made from lightweight anodized aluminum and can attach directly to an optical table or moving linear or XY actuators and can be mounted at any orientation. A precision worm gear assembly is used to transfer the rotary motion of the stepper motor into rotary motion of the carriage. The small size allows use in confined spaces, such as laser cavities, disk texturing machines, manufacturing areas for fiber optical components or semiconductor manufacturing.